Vehicle electronic power system with energy harvesting

ABSTRACT

Methods and apparatus are provided for a vehicle electronic power system. In one exemplary embodiment an energy harvesting device is configured to generate electricity in response to vibration of the vehicle occurring during normal vehicle operation. The energy harvesting device may be tuned to a frequency that falls within a peak energy region in a vibration profile of the vehicle. The power system may further include a charging circuit connecting the energy harvesting device to a rechargeable battery provides electrical power to an electro-mechanical vehicle component or system.

Provisional Patent Application Ser. No. 62/220,076, to which the presentapplication claims priority, is hereby incorporated by reference.

TECHNICAL FIELD

The technical field of the present invention relates to energyattenuating aircraft and ground vehicle seats. The technical fieldfurther relates to energy attenuating seats that self-adjust based onoccupant weight, and to vehicle electrical power systems.

BACKGROUND

Energy attenuating (“EA”) seats in military vehicles and aircraftaccount for by far most of the EA seats in use to date, and most ofthose have fixed-load, or non-adjustable energy attenuators. Whileoffering considerable crash and blast protection compared to the priornon-energy attenuating seats, protection for the so-called 5th and 95thpercentile occupants as well as the 50th percentile occupant ofnon-adjustable seats has been less than adequate. In particular, 5thpercentile occupants are subjected to higher than acceptable G loadswith a corresponding higher risk of injury, while 95th percentileoccupants risk injury caused by impact with the vehicle floor due toinefficient use of the available stroke distance and incomplete energyattenuation.

To address these shortcomings, various manually adjustable, weightcompensating energy attenuators were developed. Such systems generallyrequire the seat occupant to manually adjust a weight setting, eitherprior to or after sitting down in the seat. The selected weight settingdefines a corresponding threshold load that will cause the seat tostroke during a crash or blast event, with the goal of using all of theavailable stroking distance regardless of seat occupant weight to absorbthe crash or blast energy. While feasible in a helicopter seatapplication where the crew generally has time to follow a checklistprior to takeoff, manually adjustable systems are not well suited tomilitary ground vehicle application. The typical operating environmentfor military ground vehicles dictates a system that minimizes oreliminates any increase to the soldier's existing logistical burden.Therefore a need was recognized for an EA system that self adjusts toautomatically account for differences in occupant weight.

Various attempts to provide such a system have been proposed, includingfor example a wire-bender based system described in U.S. Pat. No.8,182,044, a tube-flattening (or crushing) based system described inU.S. Pat. No. 5,273,240, and a variable force linkage system describedin U.S. Pat. No. 5,558,301. These systems utilize a mechanicalconnection from the EA device to the seat that operates to physicallyadjust a load controlling portion of the EA device when a load is placedin the seat, and maintain the adjustment until the load is removed.

A complication arises however when the seat loading varies, as naturallyoccurs when the vehicle begins to move, and in particular when drivenover uneven terrain. Attempts to compensate for vehicle motion inducedload variation have been largely unsatisfactory, often resulting inincreased complexity of the mechanism, and in some cases requiringadditional operator input to lock or release the adjustment device. Thusa need exists for a reliable, truly automatic weight compensating EAsystem for use in ground vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is schematic depiction of an exemplary weight compensating energyattenuating seating system in accordance with the present disclosure;

FIG. 2 is a schematic depiction of an exemplary wire-bender typeadjustable energy attenuating mechanism in accordance with the presentdisclosure;

FIG. 3 illustrates an alternative configuration of the energyattenuating mechanism of FIG. 2 in which an adjustable stop moves in aperpendicular direction to a moveable roller of the energy attenuatingmechanism;

FIG. 4 illustrates an alternative configuration of the adjustable stopof FIG. 3;

FIG. 5 depicts in block diagram form an exemplary electronic embodimentof the automatic energy attenuating seating system;

FIG. 6 is a cross section of an integral actuator and gear drivenadjustable stop;

FIG. 7 is a perspective view of an exemplary cantilevered piezoelectricenergy harvesting device;

FIG. 8 is a plot of actual vehicle vibration data showing a peak energyregion in the vibration profile;

FIG. 9 depicts three cantilevered piezoelectric energy harvestingdevices mounted side by side, each device tuned to a differentfrequency.

FIG. 10 depicts an energy harvesting device configured to automaticallytune itself to real time vehicle vibration data; and

FIG. 11 is a schematic representation of an exemplary mechanicalembodiment of the automatic energy attenuating seating system.

DESCRIPTION OF THE EMBODIMENTS

The instant invention is described more fully hereinafter with referenceto the accompanying drawings and/or photographs, in which one or moreexemplary embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be operative,enabling, and complete. Accordingly, the particular arrangementsdisclosed are meant to be illustrative only and not limiting as to thescope of the invention. Moreover, many embodiments, such as adaptations,variations, modifications, and equivalent arrangements, will beimplicitly disclosed by the embodiments described herein and fall withinthe scope of the present invention.

Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation. Unlessotherwise expressly defined herein, such terms are intended to be giventheir broad ordinary and customary meaning not inconsistent with thatapplicable in the relevant industry and without restriction to anyspecific embodiment hereinafter described. As used herein, the article“a” is intended to include one or more items. Where only one item isintended, the term “one”, “single”, or similar language is used. Whenused herein to join a list of items, the term “or” denotes at least oneof the items, but does not exclude a plurality of items of the list.

For exemplary methods or processes of the invention, the sequence and/orarrangement of steps described herein are illustrative and notrestrictive. Accordingly, it should be understood that, although stepsof various processes or methods may be shown and described as being in asequence or temporal arrangement, the steps of any such processes ormethods are not limited to being carried out in any particular sequenceor arrangement, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and arrangements while still falling within thescope of the present invention.

Additionally, any references to advantages, benefits, unexpectedresults, or operability of the present invention are not intended as anaffirmation that the invention has been previously reduced to practiceor that any testing has been performed. Likewise, unless statedotherwise, use of verbs in the past tense (present perfect or preterit)is not intended to indicate or imply that the invention has beenpreviously reduced to practice or that any testing has been performed.

Referring now to the drawings, an exemplary seating system in accordancewith the present disclosure is schematically represented in FIG. 1 andindicated generally at reference numeral 10. The seating system 10consists of a seat 11, an adjustable energy attenuating (EA) mechanism12 disposed between the seat 11 and vehicle structure 23 (or between theseat and a fixed seat frame), a weight detector 13 responsive to thepresence and weight of an occupant in the seat; a signal processor 14configured to receive a real time weight signal from the weight detectorand output an adjustment signal 19; an actuator 18 configured to convertthe adjustment signal 19 into mechanical motion; and a moveable stop 20(see FIGS. 2 through 4) connected to the actuator 18.

EA devices associated with vehicle and aircraft seats come in variousforms, most commonly as devices that attenuate energy by permanently (orplastically) deforming metal. Some well known examples of the metaldeformation types include tube inversion, tube flattening, bendable rodor “link”, and wire bending devices. The EA mechanism depicted hereinbeginning with FIG. 2 is intended to represent the wire (or strip)bending type, in which energy attenuation occurs as an elongated metalbar (or wire) is pulled through a series of rollers 25. As is the casefor all metal deformation EA types, a wire bending device is configuredto prevent any deformation or movement from occurring until the appliedload exceeds some pre-determined threshold value typically associatedwith a crash or blast event. Adjustability for the purpose ofcompensating for occupant weight variation is obtained by manuallyadjusting a threshold load setting feature, typically an adjustableportion that controls the amount of deformation of the plasticallydeformable member that must occur for the seat to begin to stroke. Inthe case of a wire bending device, the deformation controlling featureis typically one of the rollers 25, and the threshold force may beconveniently adjusted by simply moving the adjustable roller to vary thealignment, or offset of the rollers. Similarly, in a tube flattening orcrushing type EA device, the deformation controlling feature is aconstriction or mandrel, sometimes with rollers, and the threshold forcemay be adjusted by varying the size of the constriction that the tube isforced through.

While the system of the present invention is described in detail usingas an example a wire bending type EA mechanism in which an initial gapis created between an adjustable stop and a moveable roller of the EAdevice, the system applies to any metal deformation type of EA device.For example, in a device that uses multiple indenting rollers positionedaround a tube, the stop may comprise an adjustable diameter ring thatconstrains the rollers from moving away from the tube. As explained ingreater detail below using the wire bending type example, until thesystem is activated by a catastrophic loading event, a gap separates thestop component from the moveable, deformation controlling feature of theEA mechanism. Because of this gap, the stop is freely moveable andadjustable by the system without interference or resistance from the EAdevice, regardless of the particular EA mechanism involved.

The present system automatically accounts for the seat occupant's weightfor purposes of setting the stop position and initial gap, without anyaction or input by the occupant using the aforementioned weight detector13, signal processor 14, and actuator 18. The process of determiningoccupant weight and setting the gap begins at weight detector 13. Atleast some portion of the weight detector may be physically connected tothe seat, or to a seat pan, and configured to receive a continuous, orreal time input seat weight force or pressure produced by a personoccupying the seat, or by the seat and occupant combined. The seatweight force may comprise the entire weight of the seat or seatoccupant, or some proportional amount. The weight detector operates toconvert the input seat weight force or pressure to a real time weightsignal 16.

The specific nature of the weight signal 16 may vary depending upon thenature of the weight detector and the overall system. For example, theautomatic system may be electronic, in which case the weight signal 16may be an electrical signal. Alternatively, the system may be fluidbased, in which case weight signal 16 may be a hydraulic pressure.Regardless, the weight signal 16 is proportional in real time to theforce or pressure produced by the seat or seated occupant, includingincreases and decreases in the seat weight force that may occur when theoccupant initially sits down, or as a result of accelerations caused byvehicle operation.

The output from the weight detector is input to a signal processor 14configured to generate an energy attenuator adjustment signal 19corresponding to a static or motionless weight of the seated occupant.In other words, a weight that excludes variations due to vehicle motionor movement of the occupant, hereinafter referred to simply as the“occupant weight”, or the “weight of the seated occupant”. Againdepending upon the nature of the overall system, such as electronic ormechanical, the signal processor may perform one or several functions togenerate the adjustment signal 19. For example, the signal processor maysimply operate as a low pass filter that removes high frequencyvariations from the weight signal. Alternatively, the signal processormay be configured to determine the weight of a seated occupant, andproduce an energy attenuator adjustment signal based on that weight. Inan electronic system for instance, the signal processor may include afilter, an algorithm configured to determine an occupant weight, and alook-up table to select an EA adjustment instruction.

The EA adjustment signal 19 from the signal processor is input to theactuator 18. Using the adjustment signal, the actuator 18 then operatesto adjust the load setting feature of the EA system so as to account forthe weight of the seat occupant. A power source may or may not berequired to operate the actuator and other system elements dependingagain on the nature of the overall system.

FIG. 2 schematically depicts a three-roller adjustable wire bending typeEA device 12 in which a center roller 27 is mounted on a slider 29guided by openings 30 in opposite sides of EA housing 33. The rollersdefine a serpentine path for a deformable metal rod 22, causing it toyield and permanently deform several times as it passes through therollers, or as the rollers are pulled along the bar. Bar 22 may beround, square, or flat in cross section, and is typically referred to asa wire, strip, bar, or rod, any of which may be used hereinterchangeably to mean element 22 of the drawings. In EA seatapplications, the metal rod is usually fixed at an upper end to a seatframe or vehicle structure, while the rollers are attached to the seatand move with it as the seat strokes downward during a crash or blastevent.

The slider 29 and center roller 27 are moveable laterally between afirst position shown in solid lines that corresponds to a minimum rolleroffset, and a second position shown in dashed lines that corresponds toa maximum roller offset. On installation the slider 29 and roller 27 arein the first position (minimum roller offset), and bar 22 is pre-bent tofit around the center roller 27 in the manner shown. The amount that thebar 22 must deform, and thus the load required to pull the bar 22through the rollers (the threshold load) in the first position are bothat a maximum. Conversely, with the slider and roller in the secondposition (maximum roller offset), the bar deformation and threshold loadare both at a minimum. Thus as the roller offset increases, thethreshold load decreases, and vice versa. In that sense the rolleroffset and the threshold load are inversely proportional to one another.

When enough force is applied to bar 22 to pull it through the rollers,such as in a blast event, the bar will attempt to straighten, and in sodoing exert a lateral force (indicated by arrow ‘F’) on the centerroller 27. The lateral force F will tend to move the center roller 27and slider 29 in the direction of increasing offset, or from right toleft in FIG. 2. The amount of movement possible may be controlled anddefined using an adjustable stop 20 to set an initial gap δ between thestop and the end of the slider. The initial gap δ may be set at anydesired amount. If the initial gap is set at zero, the slider 29 willnot be able to move at all when subjected to the lateral force F. Inthat case the bar deformation and the threshold force are maintained attheir first position, maximum values. Conversely, the larger the initialgap, the farther the slider 29 will move before hitting the stop, thegreater the roller offset, and the lower the threshold force.

An object of the present system is to provide a means for adjusting thethreshold force to an appropriate level for a given seat occupant weightto ensure that the seat strokes the same distance in a crash or blastevent regardless of occupant weight. Referring still to FIG. 2, in oneembodiment the initial gap δ is adjustable between a non-zero minimumgap δ₁ associated with a maximum anticipated occupant weight; and amaximum gap δ₂ associated with a minimum anticipated occupant weight.Because the minimum gap is not zero, the slider 29 and stop 20 are bydefinition never in contact when the stop is being moved to establish oradjust the initial gap. Thus under sub-threshold loading conditions, thestop is always freely movable and adjustable without being subjected toexternal forces or friction, such as from the bar and roller mechanismof an adjustable wire bender device.

To ensure that the slider does not interfere with the stop, themechanism may include a temporary restraint 34 configured to hold theslider in the first position under sub-threshold loading conditions, andyet readily release the slider when subjected to a lateral load by adeforming bar 22. The temporary restraint may be of a detent type thatuses friction to secure the slider such as the flexible clipconfiguration shown, or a more positive configuration such as a shearpin and the like.

The arrangement, orientation, and movement direction of the actuator,stop, and EA mechanism may take various configurations. In theembodiment of FIGS. 1 and 2, the actuator 18 is oriented to move thestop 20 along a longitudinal axis directly toward or away from the endof slider 29. FIG. 3 schematically depicts an alternative configurationin which the actuator is rotated 90 degrees to move the stop 20 in adirection perpendicular to the path of slider 29. The direction ofmotion is indicated by arrow 57. In this embodiment the stop 20 may havea wedge shape as shown, with the wedge oriented so that an angled side55 is juxtaposed with the end of slider 29. Thus by extending orretracting the stop with the actuator, the size of the initial gapbetween the slider and the side 55 of stop 20 may be adjusted.

The stop may be guided and supported by a fixed housing member 56positioned behind a straight side 59 of stop 20 opposite the angled side55. The housing member 56 provides a straight surface or channel alignedwith the direction of motion of the stop 20. Housing member 56 may forexample be a portion or extension of EA housing 33 that also supportsactuator 18 and control elements such as signal processor 14. Anadvantage to the configuration of FIG. 3 is that the load imparted tothe stop by the slider 29 during a high load event presses the stopagainst housing member 56, rather than against actuator 18. Because theactuator is effectively removed from the load path, it need not bedesigned to carry the potentially high direct load from the EAmechanism.

The angled side 55 of stop 20 may have a stepped shape as shown in FIG.3, presenting a series of flat surfaces to slider 29. In anotherembodiment shown in FIG. 4, side 55 presents a series of dish-shaped, orsemicircular recesses 61. In this embodiment the slider 29 of the EAdevice may have a rounded end 63 sized to fit the recesses 61. In eithercase, whether flat steps or semicircular recesses, the angled surface 55provides a series of incremental initial gap sizes between the stop andslider. Alternatively, angled side 55 may be a completely smooth inclinewithout steps or recesses, to provide a continuous or infinite initialgap size adjustment. In that case the incline angle of side 55 withrespect to the straight side 59 should be less than approximately 7degrees to avoid excessive side loading on slider 29.

FIG. 5 schematically depicts in block diagram form an exemplaryelectronic embodiment of the automatic EA seating system. The portionsof FIG. 5 corresponding to the previously identified system elements,such as weight detector 13, weight signal 16, signal processor 14, andso on are indicated, with dashed lines used to denote groupings ofblocks that correspond to a single previously defined system element. Inthe depicted embodiment the weight of a seated occupant 41 is detectedby weight detector 13 that sends an analog electronic weight signal 16to the signal processor 14. The weight detector 13 may be an electronicsensor or transducer configured to convert a physical force or pressureinto an electronic signal.

The installation and configuration of the weight sensor may take variousforms depending upon the design of the stroking seat and the EAmechanism. For example in a system in which the seat is directlysupported by the EA system, the sensor may be located within a load pathbetween the seat and the EA device, or between the EA device and thesupporting vehicle structure 23. In those configurations the sensordetects the entire weight of the seat and the seated occupant.Alternatively, the sensor may comprise one or more electronic sensingdevices built into or under a seat pan portion of the seat that sensethe weight of an occupant, independent of the seat weight.

One example of a commercially available device suitable for use asweight detector 13 is a load cell manufactured by MeasurementSpecialties of Hampton, Va. The load cell is made in a silicon fused onglass process for use in commercial products such as bathroom scales.Other suitable devices include a Delphi silicone-filled bladder systemwhich measures pressure to infer an occupant weight category or range, aGagetek/BF Goodrich system which uses torsion-sensing load cells mountedon the corners of the seat, and a Sensata piezoelectric-wire sensor thatmeasures deflection due to the presence of the occupant. The sensor orsensors may further comprise devices configured to detect the smalldisplacement of a flexure designed into the load path, or variousadaptations of existing automotive technology.

The weight signal 16 from the sensor is output to the signal processor14, and more particularly to a data acquisition and converter unit 44.The data acquisition and converter unit 44 may be configured to receiveadditional input signals, such as an acceleration signal from anoptional accelerometer 45 attached to the seat or in the vehicle. Theaccelerometer may be utilized to facilitate enhanced detection ofconditions that would tend to affect the apparent sensed load on theseat, such as when the vehicle is undergoing maneuvers or travellingover rough terrain. For example, by comparing accelerometer data to theweight sensor output, seat load variations that are not due to vehiclemotion, such as the initial impulse caused by sitting on the seat orabnormal occupant motion, may be more readily identified.

The data acquisition and converter unit 44 outputs an unfiltered digitalsignal 43 that contains the real time seat weight data, as well as anyadditional data, such as acceleration information. The unfiltered signal43 is received and processed by a digital filter 46 that removesartifacts in the signal attributable to vehicle or occupant motion. Forexample, filter 46 may operate as a low-pass filter that removesvariations in the incoming unfiltered signal that are outside apre-defined cut-off frequency range. The cut-off frequency could beselected to be below the frequency range associated with most vehiclemotion induced load variations. Alternatively, filter 46 may operate asa nonlinear filter configured to continuously or incrementally calculateand output a median signal value. In any case the filter outputs asignal that relates to and may be correlated to the weight of the seatedoccupant.

The filtered weight signal, which may be a single value or a range, isthen further processed within signal processor 14 to produce the EAadjustment signal for input to the actuator 18. The additionalprocessing may include a static weight algorithm 47 that determines aweight value for the seated occupant from the filtered weight signal,and a look-up table 49 that operates to select and output an adjustmentinstruction 50 based on the calculated occupant weight value. The staticweight algorithm 47 may also be configured to convert a filtered weightsignal based on a combined seat and occupant weight to a weight of justthe seated occupant. The adjustment instruction 50 goes to a drivercircuit 51 configured to output the EA adjustment signal 19 in the formof a voltage signal.

The actuator 18 receives the voltage signal and positions the stop 20accordingly to provide the appropriate initial gap δ for the particularseated occupant. The actuator 18 may be a commercially availablesolenoid (or servo) device. Suitable rotary solenoid devices areavailable for example from Impulse Automation, headquartered in theUnited Kingdom, through their website “thesolenoidcompany.com”. Itshould be appreciated that some or all of the above described electronicsystem elements, such as the elements comprising signal processor 14,may be physically grouped together as components of a control board, assoftware or firmware elements in a CPU or computer, or as a stand-aloneCPU, laptop, or other fixed or mobile computing device.

FIG. 6 depicts one exemplary packaging arrangement of the actuator 18,stop 20, and adjustable wire bending type EA mechanism 12 for anelectronic embodiment of the system. The view depicted is a horizontalcross section in which the deformable metal rod 22 (not shown) wouldpass through the EA mechanism in a direction perpendicular to the planeof the drawing, and parallel to the stroking direction of the seat. Amotor (or servo) 71 and an EA housing 33 are mounted next to each otheron an actuator housing 73 that is in turn attached to and moveable withthe seat 11. A shaft gear 75 on the motor 71 rotates an idler gear 79that rotates a stop gear 77 on the stop 20. The stop gear is attachedto, or integral with stop 20 such that rotating gear 77 also rotates thestop. The stop 20 has an inner shaft 81 that extends from gear 77 towardseat 11 into an inner bore 78 of housing 73, and a threaded outer shaft83 that extends from gear 77 toward slider 29 of EA mechanism 12 andinto a threaded outer bore 80 of housing 73. Thus when the stop isrotated via the electric motor and gears, the outer shaft 83 screws inor out of the threaded outer bore 80, causing the stop to move toward oraway from the slider 29, and thereby adjusting the initial gap δ.

The electronic EA adjustment system need not operate continuously. Inone embodiment the system is initially in a stand-by mode, and activatedby the weight detector 13 when a person first sits down on the seat. Thesystem then proceeds through the above described process of determiningan occupant weight and positioning the EA mechanism, after which thesystem goes into a sleep mode. The determination of the occupant weightmay occur while the vehicle is stationary or when moving.

Once in sleep mode, the system is programmed to ignore furthervariations in the seat weight signal due to vehicle motion or movementof the occupant within the seat. The system will remain in sleep modeuntil conditions occur that are consistent with the seat being vacated.For example, the system may be programmed to monitor the seat weightsignal from the weight detector 13 and recognize when it goessubstantially to zero for a sufficient pre-determined length of timeindicative of the seat having been vacated. Upon determining that theseat has been vacated, the system may be configured to come out of sleepmode, and reset to stand-by mode. The system may be configured toautomatically repeat the above sequence and go into sleep mode aftereach time that another person sits down on the seat and the EA mechanismis re-adjusted.

Power to operate the system, or to charge a battery that powers thesystem, may be uniquely provided by harvesting energy from thevibrations and accelerations that occur naturally from normal vehicleoperation. Referring to FIG. 7, vehicle motion energy may be harvestedusing a cantilevered piezoelectric device 110, mounted for example tothe back of the seat (see FIG. 1). The device is configured withappropriate mass and flexibility to oscillate in response to road ormotor induced vibrations transmitted to the seat under typical drivingconditions. The oscillations generate electricity through repeatedflexing of an integral or embedded piezoelectric layer 112. One or moresuch devices may be employed, with the devices oriented in one or moredirections. For example, an installation may comprise three cantileverdevices 110, each oriented perpendicular to the other two, or in x-y-zdirections.

Instead of powering the components directly from the energy harvestingdevice, the harvested energy may be used to charge a rechargeablebattery that powers the seating system components. Charging may becarried out automatically with a suitable charging cable or circuitconfigured to provide an appropriate charging current to the battery. Inone embodiment the charging circuit is an integral element of a controlboard or CPU containing some or all of the electronic components of thesystem, such as the signal processor.

An example of a suitable commercially available cantilever device 110 isthe Volture V22B piezo device marketed by Mide Technology Corp. ofMedford Massachussets. Feasibility of using the Volture device to chargea suitable power source for the electronic EA system was evaluatedanalytically using actual vehicle vibration data. FIG. 8 depicts atypical vibration profile of a driver seat in the US Army's M88 RecoveryVehicle travelling at 20 km/hr averaged over a variety of road surfacesand terrains. The data plot shows a region of peak energy, indicated atreference numeral 108, of approximately 100 Hz. By tuning the VoltureV22B device to 100 Hz (which may or may not be the region of peak energyat other vehicle speeds), the analysis shows that the device couldproduce about 650 milli-joules per hour, enough energy to run theprocessing elements of the system, and to adjust the seat up to ninetimes per hour.

Thus, the efficiency of the energy harvesting system may be optimized byutilizing a device that is tuned to match a certain driving frequencyimparted by the vehicle. If the vehicle vibration profile exhibits apeak energy frequency region that does not vary appreciably with changesin vehicle driving speed or engine speed, power may be efficientlygenerated with an energy harvesting device, or devices, tuned to thatfrequency. However, if the vehicle vibration profile exhibits multipleenergy peaks, or if the frequency of the peak energy region varies withvehicle driving speed or engine speed, it may be advantageous to employa plurality of energy harvesting devices, each tuned to a differentfrequency. FIG. 9 depicts an example of such a system wherein threecantilever type piezoelectric devices 125, 126, 127, tuned tofrequencies f₁, f₂, f₃, respectively, are ganged together in aside-by-side mounting to the vehicle or seat structure 129. A multipledevice system of this type may be used to passively cover a wider rangeof driving frequencies without the added complexity of adjustability.

Alternatively, the energy harvesting system may include the capabilityto detect the vehicle vibration profile in real time, and automaticallytune itself to match the peak energy region of the profile. Referring toFIG. 10, the vibration profile of the vehicle is sampled in real timewith a vibration sensor 121 that may be mounted to the seat, or packagedwith other components of the energy harvesting or automatic energyattenuating systems. A tuning control 123 identifies a peak in the realtime vibration profile, and automatically adjusts the natural frequencyof the energy harvesting device to match the peak. The tuning controlmay include a processor configured to generate an adjustment signalcorresponding to the peak in the vibration profile, and a motor thatuses the signal to adjust a physical parameter of the energy harvestingdevice related to the natural frequency, such as weight, length,material stiffness, or damping. For example, a cantilevered type devicemay be mounted in an adjustable clamp that allows for changing thecantileverd length. The tuning control and sensor may be combined withthe energy harvesting device in one integrated unit, that may itself beintegrated or packaged with the electronic energy attenuating system.

Although described in terms of powering the electronic EA system, afrequency optimized piezoelectric energy harvesting device may beadvantageously employed to charge and operate various other vehicle orvehicle seat electronic and electro-mechanical systems with relativelylow or intermittent power needs. Examples include environmental,navigation, communication, internet, entertainment, head up display, andseat or mirror adjustment systems.

Referring now to FIG. 11, an exemplary mechanical embodiment of theautomatic system is schematically depicted, again identifying thefundamental elements of the system such as weight detector, signalprocessor, etc. with the previously assigned reference numerals. In thisembodiment the weight detector 13 comprises a first piston 85 in a firstcylinder 87 filled with a suitable hydraulic fluid 86. The weight of anoccupant sitting in the seat is transferred directly to the first piston85, such as through a seat pan attached to the piston, thereby causingthe first piston to compress the hydraulic fluid 86. Alternatively, thefirst piston and cylinder could be disposed in a load path between theseat and the EA device, or between the EA device and the supportingvehicle structure, whereby the entire weight of the seat and the seatedoccupant are transferred to the first piston.

The real time weight signal 16 is in the form of compressed hydraulicfluid 86 directed by a first conduit 88 to a signal processor 14configured as a flow restricting device. In one embodiment the flowrestricting device comprises an orifice 90 in a baffle 92 positioned inthe fluid path. The orifice functions as a low pass filter byrestricting fluid flow, and thereby increasing the time required toequalize pressure across the orifice. By proper sizing of the orifice,variations in the hydraulic pressure caused by high frequency variationsin the seat loading, such as from vehicle movement or engine vibration,are effectively removed from the hydraulic signal.

The EA adjustment signal is also in the form of compressed hydraulicfluid in a second conduit 94 that connects the signal processor 14 tothe actuator 18. In this embodiment the actuator comprises a secondpiston 101 in a second cylinder 102, and a compression spring 104. Thepressurized hydraulic fluid displaces the piston until the pressureforce of the fluid and the resisting force of the compression springreach a balance. The second piston is connected to the load settingdevice of the EA mechanism, such as to stop 20 (not shown), and thusdetermines the adjustment or initial gap appropriate for the particularseated occupant.

When connected to a stop 20, the second piston 101 may be configured inthe manner of FIG. 1, where the path of movement of the piston and theEA slider are parallel or aligned with one another, or in the manner ofFIG. 3 with the piston and stop moving perpendicular to the slider path.When aligned as in FIG. 1, the instantaneous loading from the EA sliderin a high energy loading event is reacted directly by the piston 101instead of by a separate structural member. Since the hydraulic fluid isincompressible, in order for the piston 101 to move, it must forcehydraulic fluid back through the orifice 90. If the area of the orificeis small enough, the piston will be unable to force any appreciableamount of fluid through the orifice in the brief time frame of a highenergy loading event. Thus through proper sizing of the orifice, theposition of the EA slider and roller will remain substantially fixed bythe second piston 101 during the event. In any case the area of orifice90 is substantially less than the cross sectional area of the fluidconduits 88, 94, and may be an order of magnitude less, or even smaller.

Since fluid must be displaced by the first piston to move the secondpiston and adjust the EA mechanism, some of the available seat strokingdistance is lost in the adjustment process. It is therefore desirablefor the first piston to displace the necessary volume of fluid with aslittle stroke as possible. On the other hand, the second piston mayrequire a relatively long stroke to provide adequate range of motion forthe stop 20, depending on the particular actuator and stop arrangement.Because both pistons operate on the same fluid volume, the ratio of thestroke lengths of the two pistons is proportional to the ratio of thepiston areas. Since the piston area is determined by the pistondiameter, a desired stroke length ratio may be obtained by properselection of piston diameters. Or, knowing both stroke lengths and onepiston diameter, the other piston diameter may be determined.

For example, assuming desired stroke lengths of 0.5 and 4.5 inches forthe first and second pistons respectively, and a diameter of 1 inch forthe second piston, the required diameter of the first piston would be 3inches. As an alternative to one large diameter first piston, severalsmaller diameter pistons could be used instead, such as under thecorners of a seat pan. Although shown as separate components, it shouldbe appreciated that the pistons and filter could be configured compactlyin one small unit, or together with the EA mechanism on the back of theseat or elsewhere.

For the purposes of describing and defining the present invention it isnoted that the use of relative terms, such as “substantially”,“generally”, “approximately”, and the like, are utilized herein torepresent an inherent degree of uncertainty that may be attributed toany quantitative comparison, value, measurement, or otherrepresentation. These terms are also utilized herein to represent thedegree by which a quantitative representation may vary from a statedreference without resulting in a change in the basic function of thesubject matter at issue.

Exemplary embodiments of the present invention are described above. Noelement, act, or instruction used in this description should beconstrued as important, necessary, critical, or essential to theinvention unless explicitly described as such. Although only a few ofthe exemplary embodiments have been described in detail herein, thoseskilled in the art will readily appreciate that many modifications arepossible in these exemplary embodiments without materially departingfrom the novel teachings and advantages of this invention. Accordingly,all such modifications are intended to be included within the scope ofthis invention as defined in the appended claims.

In the claims, any means-plus-function clauses are intended to clamp thestructures described herein as performing the recited function and notonly structural equivalents, but also equivalent structures. Thus,although a nail and a screw may not be structural equivalents in that anail employs a cylindrical surface to secure wooden parts together,whereas a screw employs a helical surface, in the environment offastening wooden parts, a nail and a screw may be equivalent structures.Unless the exact language “means for” (performing a particular functionor step) is recited in the claims, a construction under § 112, 6thparagraph is not intended. Additionally, it is not intended that thescope of patent protection afforded the present invention be defined byreading into any claim a limitation found herein that does notexplicitly appear in the claim itself.

What is claimed is:
 1. A vehicle electronic power system, comprising: afirst energy harvesting device configured to generate electricity inresponse to vibration of the vehicle occurring during normal vehicleoperation, wherein the first energy harvesting device is tuned to afirst frequency that falls within a first peak energy region in avibration profile of the vehicle; a rechargeable battery configured toprovide electrical power to an electro-mechanical component or system ofthe vehicle; a charging circuit connecting the first energy harvestingdevice to the rechargeable battery; a vibration sensor configured todetect a real time vibration profile of the vehicle; and a tuningcontrol configured to automatically adjust a natural frequency of thefirst energy harvesting device to correspond to a peak energy region inthe real time vibration profile.
 2. The vehicle electronic power systemof claim 1, wherein the first energy harvesting device is a cantileveredpiezoelectric device that generates electricity by oscillating inresponse to a vibration.
 3. The vehicle electronic power system of claim2, wherein the first energy harvesting device is tunable by adjusting acantilevered length of the device.
 4. The vehicle electronic powersystem of claim 1, wherein the electro-mechanical component or system isan adjustable threshold load setting feature that automaticallycompensates for variations in a detected weight of a seated occupant. 5.The vehicle electronic power system of claim 1, wherein theelectro-mechanical component or system comprises environmental controls,navigation, communication, internet, entertainment, head up display, orseat adjustment.
 6. The vehicle electronic power system of claim 1,wherein the tuning control comprises: a processor configured to identifya peak in the real time vibration profile, and generate an adjustmentsignal corresponding to the peak; and a motor that uses the adjustmentsignal to adjust a physical parameter of the first energy harvestingdevice.
 7. The vehicle electronic power system of claim 6, wherein theenergy harvesting device is a cantilevered piezoelectric device thatgenerates electricity by oscillating in response to a vibration, andwherein the physical parameter adjusted by the motor is a cantileveredlength of the device.
 8. The vehicle electronic power system of claim 1,further comprising a second energy harvesting device configured togenerate electricity in response to vibration transmitted to the seatfrom the vehicle during normal vehicle operation, wherein the secondenergy harvesting device is tuned to a second frequency that fallswithin a second peak energy region in a vibration profile of thevehicle.
 9. The vehicle electronic power system of claim 8, wherein thefirst peak energy region occurs at a first vehicle or engine speed, andthe second peak energy region occurs at a second vehicle or enginespeed.
 10. A method of providing electrical power to anelectro-mechanical component or system of a vehicle, comprising thesteps of: attaching to the vehicle an energy harvesting deviceconfigured to generate electricity in response to vibration of thevehicle occurring during normal vehicle operation, wherein the energyharvesting device is tuned to a frequency that falls within a peakenergy region in a vibration profile of the vehicle; charging a batterywith electrical current generated by the energy harvesting device duringvehicle operation; powering the electro-mechanical component or systemdirectly from the battery; detecting a real time vibration profile ofthe vehicle during vehicle operation; and adjusting a natural frequencyof the energy harvesting device to correspond to a peak energy region inthe real time vibration profile.
 11. The method of claim 10, wherein theenergy harvesting device is a cantilevered piezoelectric device thatgenerates electricity by oscillating in response to a vibration.
 12. Themethod of claim 11, further comprising the step of adjusting a naturalfrequency of the cantilevered piezoelectric device.
 13. The method ofclaim 10, further comprising the steps of: identifying a peak energyregion in the real time vibration profile of the vehicle; generating anadjustment signal corresponding to the peak energy region in the realtime vibration profile; and adjusting a physical parameter of the energyharvesting device based on the adjustment signal.
 14. The method ofclaim 13, wherein the energy harvesting device is a cantileveredpiezoelectric device that generates electricity by oscillating inresponse to a vibration, and wherein the physical parameter of theenergy harvesting device is a cantilevered length of the device.